Finite Element Analysis of the Behaviour of Reinforced Concrete Columns Confined by Overlapping Hoops Subjected to Rapid Concentric Loading

Abstract

The strain rate sensitivity of concrete material was discovered approximately one hundred years ago, and it has a marked effect on the behaviour of concrete members subjected to dynamic loadings such as strong earthquake and impact loading. Because of the great importance of the confined reinforced concrete (RC) columns in RC structures, the dynamic behaviour of the columns induced by the strain rate effect has been studied, but only few experiments and analyses have been conducted. To investigate the behaviour of overlapping hoop-confined square reinforced normal-strength concrete columns, considering the strain rate effect at a strain rate of 10 -5 /sec to 10 -1 /sec induced by earthquake excitation, an explicit dynamic finite element analysis (FEA) model was developed in ABAQUS to predict the behaviour of confined RC columns subjected to the rapid concentric loading. A locally modified stress-strain relation of confined concrete with the strain rate sensitivity of the concrete material and the confining effect of overlapping hoops were proposed to complete the simulation of the dynamic behaviour of concrete with the concrete plastic-constitutive model in ABAQUS. The finite element predictions are consistent with the existing test results. Based on the FEA model, a parametric investigation was conducted to capture more information about the behaviour of confined RC columns under varying loading rates.

Parametric Analysis of the Dynamic Behaviour of Rc Columns With the Confinement Effect of Overlapping Hoops Subjected to Lateral Rapid Loadings

“…Figure 3(a) shows the descending branches of F- curves become obviously steeper with the loading rate increasing when the axial load ratio is 0.8. However, increasing the volumetric ratio of stirrups the effect of loading rate on the slope of the descending branches of F- curves becomes weaker, which is shown in Figure 3 (1) Lateral load F versus displacement  curves Figure 4 shows the similar influence of the axial load ratio n and volumetric ratio of stirrups sv on F-curves for quasi-static and rapid loadings. When the axial load ratio n is between 0.0 and 0.6, the lateral bearing capacity of columns increases as the axial load ratio increases, but the ductility decreases.…”

“…The finite element model was developed by the author [1], which has been verified by the experiment on axial compression RC column confined by type-A and type-B overlapping hoops at low and high strain rates, was used to investigate the strain rate effect on the behaviour of the RC column under lateral rapid loadings. As shown in Figure 2, a half model with symmetric boundaries on the Y-Z plane was used based on the symmetry, which reduced the computation cost.…”

“…Many studies have demonstrated that the strain rate sensitivity of concrete and reinforcing steel significantly affect the RC members and structures [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. The strain rate sensitivity indicates the change in properties of these materials with the increase in strain rate of concrete and reinforcing steel.…”

“…Fewer experimental studies [17][18] have been conducted on confined RC columns under concentric compressive rapid loadings. To make up for the lack of experimental studies, the finite element analysis method was used to analyse the dynamic compressive behaviour of confined RC columns [1,3,8], but there is no study on the confined RC columns subjected to lateral rapid loadings. Because of the high requirement on loading instrument for the rapid loading test, the FEA modelling becomes a good choice for parametric studies.…”

“…In this paper, the objective is to investigate the strain rate effect on the dynamic behaviour of reinforced concrete columns confined by overlapping hoops under lateral rapid loadings using finite element analysis. The finite element model developed by the author [1] is used, which considers the confining effect of the overlapping hoops and strain rate effect of concrete and steel. The effect of the parameters, including the lateral loading rate, axial load ratio, volumetric ratios of transverse reinforcement, shear span ratio and configuration of hoops (type A and type B in Figure 1), on the dynamic behaviour of confined RC columns were investigated.…”